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that's b/c AGA has the correct tools to drill the holes. i'm pretty sure they have a drill press do it or some automated system instead of a guy w/ a drill. that way, they get cleaner and more consistent holes before they temper the glass, which they usually do on the bottom.

Originally posted by Superorb that's b/c AGA has the correct tools to drill the holes. i'm pretty sure they have a drill press do it or some automated system instead of a guy w/ a drill. that way, they get cleaner and more consistent holes before they temper the glass, which they usually do on the bottom.

Agreed. I am sure that they have a press and a very systematic, organized system for placing the holes. Any yes the bottom pane of glass is tempered (and sometimes thicker glass) due to the increased stress that the bottom piece is subjected to (weight of water, dropping/falling rocks, etc.).
My point is that placing holes in a glass tank is a task that can be accomplished by people other than the tank manufacturer. Myself and several friends have done it with a simple cordless or corded drill and a few different sizes of diamond coated hole saws off of Ebay with great success. The other point of information that was attempted to be shared with the members of the board is that Ebay has much cheaper hole saws than:

Ok, i didn't get mine from lau. i got mine from www.richontools.com DONT get them from this guy. ALL his hole saws are flawed. wish i knew bout the ones form lau being straight. i thought they were all a little un true. oh well... i got the holes drilled already, just took FOREVER to drill the dam mthings...

I just received my 60 mm hole saw from Lau. I used it to cut 2 holes in my new tank. Although it worked, I got some small chips on the holes. They are not too bad and I dont think will cause a problem. IT IS VERY IMPORTANT TO USE DUCT TAPE ON THE INSIDE OF THE TANK. I did this with my second hole and it was much better.
The shaft was not strait so the bit and drill wobbled when I used them. I e-mailed Lau about this and I'll let you know what he says in response.

Can you explain what the duct tape does on the inside of the tank. Assuming that you are placing it on the other side of where you are drilling. I am guessing it is to keep the drilled glass in place so you can remove it easier or does it serve another purpose?

When I placed duct tape on the inside of the tank where I was drilling the hole, the glass piece I was cutting out stayed in place until I was completely finished with the cut. On my first hole, the glass piece wasn't completely finished being cut and because of its weight, it broke away from the cutting and made a small chip in the edge of the hole.

see that's what happened to me on my first hole. the saw b/c it was a bit wobbly popped the core out and it left small chips around the hole. next 2 holes i hot glued a piece of wood to the glass, this way the glass didnt move and it was much cleaner.

as for not taking a while, i asked a glass shop how fast i could turn the drill, they said nothing more than 300rpms when cutting glass like that w/o a press, b'c if it's spinning real fast, than there's greater chance to slip or anythign else to happen. theres a website on this saying how it causes much stress to drill the hole really fast. i drilled all 3 of mine on a real slow setting. ya, it took longer, but it didnt put hardly any stress on the glass as opposed to going ape **** and making the drill go at full speed.

Having said that it is important to realise there are two reasons for the speed

The hole saws were intended to be used with a drill press like jig. These jig usually have two speeds 200-300 rpm and 1000 -1500 rpm. Starting at 1000-1500 rpm is asking for trouble.

The second reason is more related to the grinding process. Higher speed less bit life, increased chance of the bit binding and glass cracking, lower hole quality, inabilty to clear the glass waste resulting in slower grinding etc.

Most of the second reasons are unlike to be the concern of the average person grinding a handful of holes.

Even if you are going slow, if the bit binds and wrenches the drill from your hands you will likely crack the glass you are drilling. More powerful drill is not always better when drilling glass:LOL:.

__________________
I try to learn from other's mistakes but my own are more entertaining.

it worries me hearing of the poeple that cut a 2" hole in their tank saying, "oh man it was so quick, it only took me 3 minutes to drill the hole it was great!!" keep doing it that way and you're bound to crack the glass sometime or another.

the key is slow speed and light pressure, as well as evacuating the glass dust that the saw makes when cutting.

I cannot tell you that with any confidence. It depends on the bulkhead. Usually the manufacturer or distributor will list the min. and max. size holes that can be drilled to accomodate the bulkhead. I know for a fact that www.savko.com lists the sizes of holes for their bulkheads; both sched. 80 and sched. 40.

The above statement is absolutely NOT true. Many tank manufacturers make 55's with untempered glass.
Ocean View Aquariums - not tempered
GlassCages - not tempered

P.S. - I disagree with using silicon on bulkheads. If installed correctly, silicon should never need to be used. I have installed hundreds of bulkheads in tanks (both my own, and customers' tanks) and never used silicon. In over 12 years, I have never had a bulkhead leak. Even some manufacturer's directions say not to overtighten, and not to use silicon.

Originally posted by Rendos
P.S. - I disagree with using silicon on bulkheads. If installed correctly, silicon should never need to be used. I have installed hundreds of bulkheads in tanks (both my own, and customers' tanks) and never used silicon. In over 12 years, I have never had a bulkhead leak. Even some manufacturer's directions say not to overtighten, and not to use silicon.

What would be the harm in using silicone if gives a person peace of mind?

I would have to agree about the 55g tanks not always being tempered. When I contacted AGA they said that the bottom of all the 55g tanks came tempered, and the only way they tempered the front/back is if it came in a "combo" is what she said. But, you can also measure the glass on the sides and front/rear and relay that to AGA and they can tell you if it's tempered or not.

Originally posted by jimroth Okay, Superorb, Can you tell me what mm size works for a 2" bulkhead? The tank I'm cutting it in is so old I don't care if it cracks.

jimroth...
You can try this webpage. http://www.marinedepot.com/aquarium_..._strainers.asp
MarineDepot lists the size hole in your glass tank for the Bulkheads that they sell. The units are given in inches however so you will need to convert this to millimeters.
(1 inch equals 25.4001 millimeters)
Or you measure the outside diameter of your Bulkhead.
The problem with giving you an exact number is that it depends on the brand of the BH and Sched 40 vs 80.
Hope this helps some.

Originally posted by causeofhim What would be the harm in using silicone if gives a person peace of mind?

Rendos shares an opinion that I have heard before. Many people do not use Silicone when installing BHs and they perform leak free. I, myself have always used Silicone with my BHs and have been leakfree so I will continue with what works for me.

Sched 40 BHs are weaker and can crack if overtightened. I think that people sometimes overtighten these lighter duty BHs when not using Silicone and this can lead to an immediate leak or possibly a leak somewhere down the road when the stress starts to split the threads. Not good. This is why I recommend Silicone and tighten "only" very tight. I am afraid that the average person may attempt to apply Super Gorilla strength if they are not using Silicone and possible crack their Sched 40 BH.
Sched 80 BHs are more "beefy" and come with a Great Gasket. I would have no problems not using silicone on these as long as I had good access to the unit when installing it and could tighten it down really well.
I have heard some claim that the Silicone can/may deteriorate the rubber gasket of the BH over time. I do not know if this is true or not. I have never found this to be true in any of my experiences but I dont know for sure.
So to finally get to your question causeofhim the silicone MAY not play nice with the BH's rubber gasket.
With that said... I have plenty peace of mind with all of my siliconed BHs in my young and old tanks.
Cheers